[Feature Request] Jellyfin - load subtitles when when casting to MPV

[stexus]

Is your feature request related to a problem? Please describe.
I currently can only use asbplayer on Jellyfin Web, and it works wonderfully. However, I normally play off Jellyfin via the mpv-shim, which causes no video to open up on the web version, but it DOES still allow control via the web with a playback bar -- essentially everything is on the web except the video itself.

Describe the solution you'd like
I'm wondering if it's feasible to still have asbplayer "detect" this as a video and load the subtitles still.

Additional context
The flow I'd like is to be able to still have a subtitle follower on the browser but do the card creation via mpv (with a plugin such as mpvacious).